The present application claims priority to Japanese Application No. P11-332627 filed Nov. 24, 1999, which application is incorporated herein by reference to the extent permitted by law.
1. Field of the Invention
This invention relates to a cartridge-contained recording medium especially suitable for application to a disc contained in a cartridge and having a printed layer on at least one surface.
2. Description of the Related Arts
Magneto-optical recording is made by irradiating a laser beam onto a signal recording layer and simultaneously applying a magnetic field from a magnetic head in a record/reproduce apparatus. There is MD (Mini Disc), for example, as a magneto-optical recording medium used for such magneto-optical recording.
Magneto-optical recording mediums typically have a multi-layered structure sequentially stacking a first dielectric layer, signal recording layer, second dielectric layer and light reflecting layer on a substrate. Further formed on the light reflecting layer is a protective film.
Recently proposed was a magneto-optical recording medium with a colored protective film to conform to the consumer preference.
Magneto-optical recording mediums with colored protective films have more factors that appeal to one""s eyes than conventionally used magneto-optical recording mediums. Therefore, they can meet user""s requirements more easily. However, it was still difficult to distinguish products in accordance with increased demands from users for distinctiveness and progressively variable users"" tastes.
As a method for meeting users"" demands for distinctiveness and satisfying a variety of tastes, printing on disc planes was proposed.
However, printing on disc planes caused corrosion of discs by ink and degradation in accuracy of magnetic heads by deterioration of surface qualities derived from uneven printed planes.
It is therefore an object of the invention to provide a cartridge-contained recording medium that has a sufficient resistance to corrosion even when a print is applied onto at least one surface of the recording medium and simultaneously has good slidableness.
According to the invention, there is provided a cartridge-contained recording medium in which a recording medium is contained in a cartridge, characterized in a first dielectric layer, a signal recording layer, a second dielectric layer, a light reflecting layer, a first protective layer, a print layer and a second protective layer are sequentially stacked on a base body of the recording medium; and the second protective layer has a thickness not smaller than that of the print layer.
In the present invention, for the purpose of improving the resistance to corrosion of the recording medium and obtain good slidableness, thickness of the second protective film is preferably larger than that of the print layer.
In the present invention, for the purpose of ensuring a sufficient resistance to corrosion of the recording medium and forming a print layer on a good plane, thickness of the first protective film is typically not smaller than 2 xcexcm.
In the present invention, for the purpose of preventing damages to the surface of the recording medium, thickness of the second protective film is typically not smaller than 5 xcexcm.
In the present invention, for the purpose of ensuring the effect of sufficiently masking unevenness of the print layer and obtaining a good protective property and a good recording property, thickness of the second protective layer formed on the print layer is typically not beyond the range from 1.1 times to 2.0 times of the thickness of the print layer, and preferably not beyond the range from 1.2 times to 1.5 times of the thickness of the print layer.
In the present invention, total thickness of the first protective layer, print layer and second protective layer is typically from 12 xcexcm to 20 xcexcm.
In the present invention, for the purpose of maintaining a print clean, if at lest two or more colors are used on the print layer, thickness of the print layer is typically from 3 xcexcm to 8 xcexcm, and preferably from 5 xcexcm to 6 xcexcm. Furthermore, in the present invention, if a single color is used on the print layer, thickness of the print layer is typically from 1 xcexcm to 3 xcexcm. In the present invention, for the purpose of improving visibility of printed colors, a white-colored layer is typically provided as a base layer of the print layer.
According to the cartridge-contained recording medium having the above-summarized configuration according to the invention, since the protective film formed on the print layer has a thickness not smaller than that of the print layer, possible unevenness of the print layer can be sufficiently masked by the second protective layer, and the recoding medium can be improved in smoothness of its surface.